Organic Molecular Nanotechnology: Functional Nanofibers from Functionalised P-quaterphenylenes

A new bottom-up nanotechnology approach is presented here: It starts with organic synthesis of functionalised materials and includes self-assembled growth of nanofibers, which are proven to be highly functional for future sub-micron optoelectronics. This approach combines organic chemistry (transition metal catalysed cross-coupling reactions) and physical processing and characterisation techniques (high vacuum, organic molecular beam epitaxy, atomic force microscopy, optical spectroscopy and microscopy). Therefore it is of equal interest for chemists and physicists. The organic nanofibers are grown in a self-assembly process to mutually aligned arrays on a muscovite mica substrate. They exhibit outstanding (optical) properties. Functional groups are implemented at the terminal positions of rodlike p-quaterphenylenes to generate new molecular building blocks for tailormade nanofibers. The fluorescence peak emission frequency shifts within the blue and the overall shape of the nanofibers alters depending on the functionalisation. Push-pull functionalised oligomers lead to nanofibers with strong non-linear optical response - they act as frequency doublers.